#include <func.h>

int main()
{
    int fd = open("file_change_auth", O_RDWR);
    printf("pid = %d, ppid = %d, uid = %d, gid = %d, euid = %d, egid = %d\n", \
            getpid(), getppid(), getuid(), getgid(), geteuid(), getegid());
    
    int ret = write(fd, "hello", 5);
    if (ret != -1)
        printf("I can write\n");
    close(fd);
    return 0;
}